modi 制作的300B

Hi William,

The layout of the new version seems better than previous one, using less leadwire connection. That makes me interest to dismantle my 300B to re-construct it again.

I saw that you are using a long silver like ground bus as ground wire. Can you tell me what wire gauge it is? Is it Jensen silver wire??

Regards,

Allan

Hi William,

Thanks for your information and support. I have already changed it. I spent half day to dismantled the old layout and one day to construct the new one.

The new one is now being run-in and it seems better in transparency and sound-stage improved, after using the silver wire as ground and HT line.

Besides, I can rotate one of the 300B socket by 180 deg and I can see the brand name of the tube now.

In order to get better result on 300B performance, I changed the supply tranx output to 400Vdc. It is better in dynamic. However, the plate voltage of 2-stage 6SN7 has risen up, too. Then I changed the R8 from 2.7k to 3.3k, now the plate voltage is about 260~280V depending on the quality of 5U4G.

Original plate voltage of 2-stage 6SN7 is 210Vin Gramo Audio layout, but I refered to JE lab's circuit that is 280V in this plate voltage. Should I further adjust it to go back to 210V? or can you advise the sonic difference between 210V and 280V on 2-stage of 6SN7??

Regards,

Allan